It was not possible to establish exactly when the turtle died, but Professor Godley felt the level of decomposition meant it died in UK waters or nearby.

Duncan, who sailed across the Pacific earlier this year to study the presence and impact of micro-plastics in the region, said: “Leatherback turtles are known to swallow plastic bags which they are thought to confuse with their natural jellyfish prey.

“We can confirm that this is not what killed this animal. She had partially digested food inside, as well as a piece of clear plastic. It is unfortunate that almost all turtles examined now around the world have plastic in their gut.”

Poggio-Colman, who is studying the population of leatherbacks in her native Brazil with funding from the Brazilian government, said: “Based on satellite tracking studies around the Atlantic, it is likely that this female did not come from Brazil or the largest Atlantic population in Gabon, but from the wider Caribbean area from a site like French Guiana, Trinidad or Colombia.